The number of electrical components in automotive vehicles have increased substantially in recent years. Trends suggest that the number and complexity of electrical components in vehicles will continue to increase. Many of the electrical components incorporated into automotive vehicles include a plurality of input/output signal carrying lines. For example, a typical automotive radio will include input/output lines extending to an illuminated radio dial, an electric clock incorporated into the radio dial and various power operated controls on the radio. The input/output lines for electrical components on a vehicle generally extend from a printed circuit board to an electrical connector having a plurality of terminals mounted therein. The leads extending from the circuit board to the connector are likely to generate or receive electrical interference, e.g., EMI/RFI. For example, the signals generated by an automotive radio may affect or be affected by other electronic components of the vehicle, such as CB radios, electronic fuel injection systems and electronic braking controls. Additionally, interference generated by electric components on one vehicle conceivably can affect the performance of electrical components on another vehicle. The affects of electrical interference on an automotive radio can be an annoying problem. On the other hand, the affects of electrical interference on an electronic fuel injection system or an electronic braking control could be catastrophic.
Most prior art vehicular radios and other electrical automotive components include capacitors, ferrite suppressors or other such filter means incorporated into the circuitry printed on the circuit board. Although these known suppressors and filters are effective to minimize interference generated on the circuit board, they are of limited effectiveness in filtering signals in the input/output lines leading to or extending from the circuit board. These signal lines external to the circuit board now are known to generate and/or receive a very significant portion of the electrical interference.
The prior art includes filters mounted on portions of signal carrying circuits external to a circuit board. These prior art attempts have shared several significant deficiencies. In particular, most prior art electrical interference filters disposed at locations external to a circuit board have been complex and relatively expensive. Additionally, these complex prior art filters have not been well suited to long term use in a automotive environment, and are subject to failure in such an environment.
In order to solve these problems, an improved filter connector was designed as shown in U.S. Pat. No. 4,929,196, dated May 29, 1990 and assigned to the assignee of this invention. In that patent, a filter connector is provided for incorporation into a signal line of an electrical component used in a high vibration environment, such as an automotive radio. The filter connector comprises a filtering assembly having a plurality of terminals disposed in spaced relationship to a grounding plate. Chip capacitors, capacitor arrays or similar capacitor means are mounted to the grounding plate. Electrical connection is provided between the capacitors and the respective terminals. Portions of the filtering assembly including the capacitors, the grounding plate and areas on the terminals connected to the capacitors are insert molded in a nonconductive housing. As a result, the nonconductive housing defines a unitary three-dimensional nonconductive matrix which surrounds, supports and protects the various interconnected components of the filtering assembly, and prevents damage in the high vibration automotive environment. Although the filter connector of this patent shows L-shaped members coupling the terminals to the capacitors, the originally resilient members eventually are substantially encapsulated by the insert molded material which provides the primary means to prevent damage as a result of the high vibration environment.
This invention is directed to further improvements in filter connectors to solve the problems caused in high vibration environments.